1. Field of the Invention
The present invention relates to an image-recording transparent film on which images are recorded with an image-forming apparatus such as a copying machine, a printer, a plotter, and the like.
2. Description of the Related Art
In recent years, images, characters and the like are widely formed on a transparent film such as an overhead projector (OHP) sheet with an image-forming apparatus which forms the images by electrophotography, electrostatic recording, thermal transfer recording and so on, such as a copying machine, a printer, a plotter, etc. The transparent film has partly an opaque section or a highly reflective section to detect the presence, kind, side or position of the film with an optical (IR) sensor assembled in the image-forming apparatus (see Japanese Patent KOKAI Publication Nos. 244590/1985 and 74680/1988).
In the above prior arts which form the opaque section or the highly reflective section on a part of the transparent film, since a section which does not allow passage of visible light is formed, it forms a shadow which has no relationship with the recorded images when the images on the transparent film are projected on a screen by a projector. Such shadows make the images less visible since they overlap the image, and the appearance of the entire projected image is deteriorated.
To solve the above problem and avoid the deterioration of the entire projected image, it is proposed to provide a section which does not absorb visible light but absorbs light in an infrared region, on a transparent sheet such as an OHP sheet (see Japanese Patent KOKAI No. 229032/1985 and U.S. Pat. No. 5,146,087).
However, the transparent sheet having the section which does not absorb visible light but absorbs light in an infrared region has poor resistance to ultraviolet light. When such sheet is exposed to sunlight or fluorescent lighting for a long time, a dye contained in the section which does not absorb visible light but absorbs light in an infrared region discolors or fades, or a material which does not absorb visible light but absorbs light in an infrared region is decomposed so that the effect for absorbing the IR light is decreased. As a result, such section does not function as intended.
In general, when the image is formed on the OHP sheet with the image-forming apparatus, an oil is deposited on its surface. When the OHP sheet having the deposited oil is resupplied in the image-forming apparatus in error, the oil is transferred onto a sensitized drum or other part, so that it may damage the image-forming apparatus. To prevent the oil transfer or the damage of the image-forming apparatus, some means is devised on the image-forming apparatus or the OHP sheet to prevent the passage of the once image-formed sheet through the image-forming apparatus. Hitherto, only a visual inspection is possible to determine whether or not the oil is deposited on the OHP sheet after the sheet is passed through the image-forming apparatus.